EP0561124B1 - Device and method for establishing forgery attempts of a chip card reader/writer - Google Patents

Description

The invention relates to a device and a method for detecting fraud attempts on a device for reading and writing a chip card of the type mentioned in the preamble of claims 1 and 13.

Such devices are advantageously used in service systems - for example in self-collecting telephone stations (payphones) - which work with electronic chip cards.

In the event of an attempt to defraud, a modified chip card or an externally similar card with identically arranged connection points is used, at least one of the connection points being connected to an electrical supply line to a device which is present outside the writing and reading device and by means of which the attempt to defraud is carried out , The attempt at fraud can be determined by checking whether there is such an unauthorized supply.

A device of the type mentioned in the preamble of claim 1 is known (EP 0 468 848 A1), in which, with the aid of an inductive sensor and a downstream selective filter, a signal can be detected in any feed line of a card pickup, taking advantage of the fact that a chip card is processed when reading and writing signals with a known, standardized frequency.

It is also known to arrange a transmitter in the card receiver at one end of the chip card and a receiver at the other end and to use any feed line as a transmission medium, the coupling being galvanic on the transmitter side and inductive on the receiver side (EP 0 323 347 A1, FR 2 554 262, FR 2 646 260) or capacitive (FR 2 646 260), or with the coupling acting inductively on the transmitter side and inductively (EP 0 447 686) or galvanically (EP 0 454 570) on the receiver side ,

In addition, a device with an oscillator is known (FR 2 646 261), which has a frequency-determining element which is moved over the chip card, so that any feed line that is present causes a fault at the output of the oscillator.

FR 2 659 770 A1 describes a device for the detection of chip cards, the contact surfaces of which are provided with unauthorized leads for fraud purposes. The device checks the impedances between the Contact areas of the chip card before the device starts querying the chip card. The measured impedances are compared with stored setpoints. The unauthorized leads change these impedances in such a way that the device recognizes the deviation from the target values and rejects the card.

In the known devices, mechanical devices such as antennas or movable sensors are to be arranged in the card holder in the area of the chip card in such a way that they are largely protected against damage.

The invention is based on the object of specifying a reliable and well-protected device and a corresponding method for reliably detecting attempts at fraud on a device for reading and writing to a chip card.

The invention solves this problem by the characterizing features of independent claims 1 and 13. Advantageous refinements result from the dependent subclaims and are characterized there.

Advantageous exemplary embodiments of the invention are explained in more detail below with reference to the drawings.

Fig. 1

das Prinzip einer Einrichtung zur Feststellung von Betrugsversuchen an einer Vorrichtung zum Lesen und Beschreiben einer Chip-Karte,

Fig. 2

eine Variante der Einrichtung mit einem Leiter als Resonator,

Fig. 3

eine Variante der Einrichtung mit einem Parallelschwingkreis als Resonator,

Fig. 4

eine Variante der Einrichtung mit einem Serieschwingkreis als Resonator,

Fig. 5a

eine Variante der Einrichtung im Aufriss,

Fig. 5b

Teile der Einrichtung nach Fig. 5a im Seitenriss,

Fig. 6

eine Variante der Einrichtung mit einem mindestens zwei Abgriffe aufweisenden Leiter als Resonator,

Fig. 7

ein ausführliches Blockschaltbild einer Variante der Einrichtung mit einem Resonator nach Fig. 6 und

Fig. 8

ein Ausführungsbeispiel eines Resonators nach Fig. 6.

Show it:

Fig. 1

the principle of a device for the detection of fraud attempts on a device for reading and writing a chip card,

Fig. 2

a variant of the device with a conductor as a resonator,

Fig. 3

a variant of the device with a parallel resonant circuit as a resonator,

Fig. 4

a variant of the device with a series resonant circuit as a resonator,

Fig. 5a

a variant of the facility in elevation,

Fig. 5b

Parts of the device according to Fig. 5a in side elevation,

Fig. 6

a variant of the device with a conductor having at least two taps as a resonator,

Fig. 7

a detailed block diagram of a variant of the device with a resonator according to FIGS. 6 and

Fig. 8

an embodiment of a resonator according to FIG. 6.

In FIG. 1, 1 means a resonator which is galvanically coupled to a contacting element 2 of a known device (chip card reader / writer) for reading and writing to a memory of a likewise known chip card 3 and which is connected to a generator 4 and an impedance converter 5 forms a resonance unit 6, the output of the generator 4 being connected to the resonator 1 via the impedance converter 5. A measuring device 7 with an alarm output 8 for an alarm signal has at least one input connected to the resonance unit 6 and an output which is fed back to the resonance unit 6 via an actuator 9.

In addition to the contacting element 2, the device for reading and writing to the memory of the chip card 3 has further similar, but not shown contacting elements, a processing unit 10 and a card receiver (not shown in the drawing) with an input opening for the chip card 3. Each of the contacting elements is connected to the processing unit 10 via an electrical line 11.

The chip card 3 is a prepaid card which has at least one electronic component, for example a microcomputer or a memory, which can be accessed via a number of connection points 12 for the writing and reading device, which has a contacting element 2 for each of the connection points 12. The number of connection points 12 and their arrangement on the chip card 3 is standardized, although different standards exist.

In an attempt to defraud, it is known that a modified chip card 3 or an externally similar card with the identically arranged connection points 12 is preferably used, at least one of the connection points 12 being connected to an electrical lead 13 of a device 14 present outside the device. If the chip card is handed over to the device, any existing supply line 13 is connected to the corresponding contacting element 2. The device 14 used to attempt fraud is, for example, a measuring device or a simulator.

A device for ascertaining the attempt to defraud by connecting the feed line 13 to the contacting element 2 consists of the resonance unit 6, the measuring device 7, the actuator 9 and a shielding means 15 which is arranged between the resonance unit 6 and the lines 11; Details of the facility and its function are described below.

The generator 4, the output impedance of which is matched to the resonator 1 by the impedance converter 5, generates an electromagnetic oscillation in the resonator 1 with a frequency of, for example, one GHz.

The resonance unit 6 is preferably coordinated such that a standing wave builds up in the resonator 1 at least when the feed line 13 to the connection point 12 connected to the resonator 1 via the contacting element 2 is missing. Through the feed line 13, the properties of the resonator disturbed so that its input impedance and the vibration are measurably changed.

Advantageously, the resonator 1 according to FIG. 2 is an electrical conductor or a waveguide, which is in the form of a wire, a strand, a conductor track or a hollow body, and which has at least one tap A, which is galvanically connected to the input of the Measuring device 7 is connected. The tap A is preferably in the vicinity of a node of the standing wave.

In a first variant of the device, the measuring device 7 measures the electrical voltage at the tap A and compares the measured value with a predetermined target value of the voltage which is present at the tap A when the supply line 13 is not connected to the contacting element 2. On the basis of the size of the difference between the measured value and the target value, an attempt at fraud is recognized and the alarm signal is generated, for example, at the output of a threshold switch belonging to the measuring device 7.

The measuring device 7 advantageously has processing means such as amplifiers or filters so that the measured value can be reliably detected.

The alarm signal is advantageously evaluated by the processing unit 10 in a known manner.

The actuator 9 enables the measured value to react on the generator 4 and / or the impedance converter 5, so that the frequency of the generator 4 and the output-side impedance of the impedance converter 5 can be changed by the measuring device 7 if necessary.

On the one hand, the shielding means 15 protects the processing unit 10 against disturbances caused by the resonance unit 6, and on the other hand it protects the device from disturbing influences of the lines 11.

In a second variant, the voltage or the impedance at the input of the resonator 1 is advantageously measured and compared with a predetermined target value of the impedance or the voltage. The target value is the impedance of the resonator 1 or the voltage at the resonator 1 without the lead 13 at the contacting element 2.

The first and the second variant can be successfully combined.

In a third variant of the device, a change in generator 4 changes the frequency of the oscillation in resonator 1 until the voltage at tap A reaches a certain target value. The target value is equal to that value of the voltage which is at a predetermined target value of the frequency of the oscillation at the tap A, provided the lead 13 is not connected to the contacting element 2. The measuring device 7 determines a measured value of the frequency of the vibration, for example via a further input connected to the output of the generator, and compares the measured value with the nominal value of the frequency. An attempt to defraud is detected based on the size of the difference between the measured value and the target value.

The third and the second variant can be successfully combined.

In a fourth variant of the device, the resonator 1 is either a parallel resonant circuit consisting of a coil L _p and a capacitor C _p according to FIG. 3 or a series resonant circuit consisting of a coil L _s and a capacitor C _s according to FIG the supply line 13 (Fig. 1) is changed. In this variant, the voltage or the impedance at the input E of the resonator 1 is advantageously measured and compared with a predetermined target value of the impedance or the voltage which the resonator 1 has on the contacting element 2 without the lead 13.

Because the electrical properties of the resonance unit 6, which is galvanically connected to the contacting element 2 and operates in the gigahertz range, are measurably influenced by a feed line 13 in the device, a feed line 13 can be reliably determined regardless of its diameter, its position or its shielding ,

The device can be arranged completely outside the card holder, since it is only coupled to the contacting element 2. In the space between the electronic module (microcomputer or memory) of the chip card 3 and the input opening of the card holder, no precautions are necessary.

The resonator 1 is preferably coupled to that contacting element 2 which contacts the potential reference point (signal ground) of the chip card 3.

5, instead of the galvanic connection to the contacting element 2 (FIG. 1), the resonator 1 has a coupling element 16 for a non-galvanic coupling of the resonator 1 to the connection points 12 and thus to the feed line 13. The coupling is capacitive or inductive depending on the type of coupling element 16.

For a capacitive coupling of the resonator 1, the coupling member 16 is designed such that a voltage at the output of the resonator 1 is influenced by the supply line 13 via an electric field.

The coupling element 16 for a capacitive coupling advantageously has a layer 17 made of a metal which is parallel to the two largest flat surfaces of the chip card 3 and which is arranged opposite a zone delimiting the connection points 12 of the chip card 3 and approximately the area of the Zone covers.

The coupling element is for an inductive coupling of the resonator 1 16 designed such that a current in the resonator 1 is influenced by the supply line 13 via a magnetic field.

The electrical lead 13 coupled to the resonator 1 via the coupling element 16 at one of the connection points 12 changes the properties of the resonator 1 detected by the measuring device 7.

With further implementation of the device, the attempt at fraud can be ascertained without the connection points 12 of the chip card 3 being in galvanic connection with the contacting elements 2. The attempt at fraud can thus advantageously be ascertained before the contacting elements 2 are applied to the connection points 12 or when the chip card 3 is inserted into the device for reading and writing to the chip card, the properties of the resonator 1 advantageously being largely independent of the Contacting elements 2 and 11 of the lines.

Furthermore, the properties of the resonator 1 are largely independent of the built-in electronic component on the chip card 3; the device can therefore advantageously be used unchanged for different versions of the chip card 3.

FIG. 6 shows part of a fifth variant of the device in which the resonator 1 is an electrical conductor or waveguide, the resonator 1 having the tap A connected to the input of the measuring device 7 and being connected to the coupling element 16. The resonator 1 has a second tap B, which is connected to a further input 18 of the measuring device 7. The second tap B is preferably in the vicinity of a node of the standing wave. With the measuring device, the electrical voltage at tap A - as already described above - and also at tap B can be measured.

7 shows the resonator 1 connected to the coupling element 16 with the input E and the two taps A and B, the generator 4, the impedance converter 5, the measuring device 7 and the actuator 9. The measuring device 7 advantageously has a first input member 19 connected on the input side to the tap A, a second input member 20 connected on the input side to the second tap B, a first threshold switch 21 and a second threshold switch 22, the two threshold switches 21 and 22 being connected on the output side to the actuator 9.

The generator 4 advantageously has a phase locked loop (PLL) 23, a voltage-controlled oscillator (VCO) 24 connected on the output side to the impedance converter 5 and a low-pass filter 25 connected between the phase locked loop 23 and the oscillator 24, a frequency input 26 of the phase locked loop 23 having the at the output of the impedance converter 5 connected input E of the resonator 1 is connected and a multi-pole control input 27 of the phase locked loop 23 is connected via a bus 28 to the actuator 9.

The phase locked loop 23 is, for example, essentially realized by a module of the type MC145191.

A reference input 29 of the first threshold switch 21 is connected to a reference input 30 of the second threshold switch 22 and connected to the input E of the resonator 1 via a compensation element 31. Changes in the voltage at the input E of the resonator 1 caused by fluctuations in the ambient temperature can be compensated for by the compensation element 31 such that a reference signal at the output of the compensation element 31 or at the two reference inputs 29 and 30 is largely independent of temperature.

The first threshold switch 21 has a signal input 32, which is connected to the output of the first input element 19. A signal input 33 of the second threshold switch 22 is connected to the output of the second input element 20.

That as an electrical conductor or as a waveguide trained resonator 1, if necessary has a plurality of conductor parts coupled by coupling members, at least one of the conductor parts being displaceably arranged when required - if this is required, for example, by the structure or the functioning of the device for reading and writing to the memory of the chip card 3.

In FIG. 8, 34 means a first conductor part and 35 a second conductor part of the resonator 1 designed as a waveguide, at one end of which is the input E and the other end of which is connected to the coupling element 16. The shape of the first conductor part 34 can be adapted to the structure and the available space in the device for reading and writing to the memory of the chip card 3. The first conductor part 34 has the two taps A and B and a first coupling element 36.

One end of the second conductor part 35 is terminated with the coupling member 16 and the other with a second coupling element 37.

The first conductor part 34 is advantageously a flexible cable and a printed circuit has the coupling member 16 and the second conductor part 35 with the coupling element 37.

The first coupling element 36 lies in a plane e ₁ , a part of which is delimited by an imaginary border 38, which also includes the first coupling element 36.

The second coupling element 37 lies in a further plane e ₂ , which is advantageously parallel to the first plane e ₁ and from which a part is delimited with a further imaginary border 39, which also includes the second coupling element 37. The two imaginary borders 38 and 39 enclose congruent surfaces.

The second conductor part 35 can be displaced in the direction of an arrow 40 at least to such an extent that the two conductor parts 34 and 35 are capacitive or inductive through the two coupling elements 36 and 37 for one Wave in the resonator 1 can be optimally coupled. An advantageous coupling of the two conductor parts 34 and 35 is achieved if the two borders 38 and 39 overlap in FIG. 8.

By moving the second conductor part 35 in the direction of the arrow 40, the device for detecting attempts at fraud can be connected to the chip card 3, while it can be decoupled from the chip card by a movement in the opposite direction of the arrow 40.

If necessary, the movement in the direction of arrow 40 is caused when the card 3 is inserted into the device for reading and writing to the memory of the chip card 3.

In an advantageous embodiment of the resonator 1, the two input elements 19 and 20 are arranged directly on the corresponding tap A or B and are implemented, for example, as an SMD (surface mounted device).

If required, the two taps A and B are arranged directly next to one another on the resonator 1 or are physically designed as a tap to which the measuring device 7 can be connected.

An advantageous embodiment of the coupling members 36 and 37 can be achieved by a single turn on the first conductor part 34 or on the second conductor part 35.

The actuator 9 can be used to set at least two different values for the frequency of the generator 4, a first value being 500 MHz and a second value 455 MHz, for example.

The length of the second conductor part 35 is advantageously tuned to a quarter of the wavelength in the resonator 1 at the first value of the frequency, while the length of the first conductor part 34 is advantageously a multiple of this half wavelength.

A method is described below in which the attempt to defraud can be ascertained with the device according to FIG. 7.

In a first step, the frequency of the generator 4 is set to the first value. The voltage at tap A is detected by the first input element 19 and compared in the first threshold switch 21 with the reference signal at the reference input 29. If the detected voltage is not in an expected first range, the attempted fraud is recognized, the process is terminated and the chip card 1 is rejected.

If the voltage detected at tap A is in the expected range, the frequency of generator 4 is set to the second value in a second step. The voltage at the second tap B is detected by the second input element 20 and compared in the second threshold switch 22 with the reference signal at the reference input 30. If the detected voltage is not in an expected second range, the attempted fraud is recognized and the chip card 1 is rejected.

The chip card 1 is only accepted if, in the case of an oscillation with the first value of the frequency, the voltage detected at the tap A in a first area and in the case of an oscillation with the second value of the frequency, the voltage recorded at the second tap B in a second area lies.

The fact that a voltage is detected at the resonator 1 at at least two different values of the frequency and compared with a setpoint value, the fraud attempt can also be discovered if the effective length of the feed line 13 is a multiple of half the wavelength of the oscillation at one of the is at least two values of frequency.

7 without the supply line 13 (FIG. 1) advantageously has a first node at the first value of the frequency at tap A and a second node at the second value of the frequency at tap B.

In an advantageous method for determining the optimal first value of the frequency of the oscillation in the resonator 1, the actuator changes the frequency in a certain direction and then detects a first threshold frequency f when an output signal at the first threshold switch 21 has a first extreme value. for example a maximum - against a second extreme value occurring in the frequency range of the first node - for example against a minimum. The frequency is changed further in the same direction and a second threshold frequency f _{2 is} detected when the output signal changes from the second extreme value back to the first extreme value.

The optimal first value of the frequency is an average of the two threshold frequencies f ₁ and f ₂ ; the first value is advantageously the geometric mean (f ₁ · f ₂ ) ^{1/2 of} the two threshold frequencies f ₁ and f ₂ .

The optimal second value of the frequency is determined by transferring the described method to the second node, an output signal at the second threshold switch 22 being used.

The method for determining the two optimal values of the frequency of the oscillation in the resonator 1 can advantageously be carried out automatically. If necessary, each implementation of the facility is individually compared using the method.

Claims (19)

1. Device for determining fraud attempts, including the connection of an electric feed line (13) to a connection point (12) of a chip card (3), in an apparatus for reading and writing in a memory on the chip card (3), said device comprises a measuring unit (7) connected to a resonance unit (6) characterized in that said resonance unit (6) comprises a generator (4) producing an electromagnetic oscillation, said generator (4) being coupled to the resonator (1) feeds the contact point (12),
   and that the measuring unit (7) comprises means to detect variations of the electrical properties of the resonator (1) caused by the feed line (13).
2. Device according to claim 1 characterized in that the resonator (1) is galvanically connected to a contacting element (2) serving for contacting of the connecting point (12) of the apparatus for reading and writing on the chip card (3).
3. Device according to claim 1 characterized in that the resonator (1) is capacitively or inductively coupled to the connecting point (12) by means of a coupling member (16).
4. Device according to one of the preceding claim characterized in that the resonance unit (6) is arranged so that a standing wave can be generated in the resonator (1) at least when the electric feed line (13) is not connected.
5. Device according to one of the preceding claim characterized in that the resonator (1) is an electrical wave conductor.
6. Device according to claims 3 and 5 characterized in that the electrical wave conductor comprises a first conductor part (34) with a first coupling element (36) and a second conductor part (35) connected to a second coupling element (37) and to a coupling member (16),
   and that both conductors parts (34, 35) are arranged to be adjustable each other and to be coupled capacitively or inductively through both coupling elements (36, 37).
7. Device according to one of the claim 5 or 6, characterized in that the electric wave conductor comprises at least one tapping (A),
   that the input of the measuring unit (7) is connected to the tapping (A),
   and that said measuring unit (7) comprises means (19, 21) for measuring the voltage at said tapping (A).
8. Device according to claim 7, characterized in, that the electric wave conductor comprises a second tapping (B) which is connected to the measuring unit (7)
   and that said measuring unit (7) comprises means (20, 22) for measuring the voltage at said tapping (B).
9. Device according to claim 1 characterized in that the resonator (1) is a resonant circuit comprising a capacitor (Cs) and a coil (Ls), which is connected in series with the capacitor (Cs).
10. Device according to claim 1 characterized in that the resonator (1) is a resonant circuit comprising a capacitor (Cp) and a coil (Lp), which is connected in parallel with the capacitor (Cp).
11. Device according to one of the preceding claim characterized in that the measuring unit (7) comprises an output directed to the generator (4) through a control member (9)
    and that said control member (9) comprises means to switch the frequency of the electromagnetic oscillation generated by the generator (4) in the resonator (1), where the number of frequencies adjustable by the control member (9) being at least set at two values f1, f2.
12. Device according to one of the preceding claim characterized in that the generator (4) comprises a phase control circuit (23), a voltage controlled oscillator (24) connected to an impedance converter (5) at the output of said generator (4) and a switching low pass filter (25) connected between the phase control circuit (23) and the oscillator,
    that a frequency input (26) of the phase control circuit (23) is connected to an output of the impedance converter (5),
    and that a control member (9) for adjusting and/or driving the frequency of the generator (4) with the mean of a bus (28) is connected to a driving input (27) of the phase control circuit (23).
13. Process for determining fraud attempts, through the connection of an electric feed line (13) to a connection point (12) of a chip card (3), in an apparatus for reading and writing a memory of said chip card (3), characterized in that,
    an electromagnetic oscillation is produced in a resonator (1) with the mean of a generator (4),
    the resonator (1) is coupled to the connection point (12)
    and that the variation of the electric properties of the resonator (1), caused by the feed line (13), is detected with the mean of a measuring unit (7)
14. Process according to claim 13 characterized in that the impedance or the voltage at the input of the resonator (1) is measured by the measuring unit (7) and compared with a predetermined reference value, which corresponds to the impedance or to the voltage at the input of the resonator (1) without the connection of the feed line (13) with the connection point (12).
15. Process according to claim 13 or 14 characterized in that the voltage of the resonator (1), which is shaped as a wave conductor equipped with a tapping (A) is measured at the tapping (A) and compared with a reference value of the voltage located on the tapping (A) when the feed line (13) is not connected to the connection point (12).
16. Process according to claim 15 characterized in that the frequency of an input signal on the resonator (1) varies as long as the voltage at the tapping (A) reaches a determined target value, the frequency of the input signal is measured and compared with a predetermined reference value of the frequency, and where the voltage at the tapping (A) having the determined target value, when the resonator (1) oscillates with the predetermined reference value of the frequency and when the feed line (13) is not connected to the connection point (12).
17. Process according to claim 15 or 16 characterized in that an electromagnetic oscillation is generated in the resonator (1) with a first frequency of the generator (4), the voltage at a first tapping (A) in the resonator (1) is measured and compared with a predetermined first reference value of the voltage, which is produced in the resonator (1) without the connection of the feed line (13) with the connection point (12),
    the frequency of the generator (4) is adjusted to a second value different from the first one,
    the voltage at a second tapping (B) in the resonator (1) is measured again and compared with an other predetermined reference value, which is measurable at the resonator (1) without the connection of the feed line (13) with the connection point (12)
    and the chip card (3) is accepted only when each voltage at the resonator (1) for the first and the second frequency value is comprised in a predetermined range.
18. Process according to claim 17 characterized in that a standing wave is generated by the generator (4) in the resonator (1) and that voltage nodes are produced, one near the tapping (A) at the first frequency f1 and one near the tapping (B) at the second frequency f2, if the resonator (1) is not coupled with the feed line (13).
19. Process according to one of the claims 13 to 18 characterized in that an alarm signal is produced by the measuring unit (7) when a fraud attempt is recognized according to the amplitude of the difference between the measured value and the associated reference value.